This invention relates to an improved self-ejecting key for drill chucks and the like.
Key devices of various types have long been used to lock and unlock drill chucks by engaging a toothed gear segment on the rotary chuck. When used, it is essential that the key device be removed to prevent it from being thrown about by the chuck as it commences to rotate. It has been known heretofore to utilize an injector means on such key devices to assure their removal from the chuck before the drill device is started. Such an arrangement is shown in U.S. Pat. No. 2,660,081. In this patent the key assembly comprised a body, a key element and a pin, all three components being integral and coaxially aligned. A bore was provided parallel to the longitudinal axis and extending through all three components. Within this bore was an ejector pin and a coiled spring retained by transverse handle in the body of the device. The ejector pin extended from one side of the pin but was prevented from extending to the outer end of the pin by an internal shoulder. The aforesaid arrangement was found to have two major disadvantages. First, since the ejector pin was prevented from extending all of the way to the outer end of the key pin, it was possible on some occasions to leave a key device partially engaged within a chuck with the usual unfavorable consequences. Secondly, the structural arrangement of the aforesaid patented key device made it relatively expensive to manufacture, particularly in large quantities.
Accordingly, a general object of the invention is to overcome the aforesaid disadvantages and provide an improved self-ejecting key device for drill chucks.
Another more specific object of the present invention is to provide a self-ejecting key device for drill chucks which assures positive ejection from the chuck each time it is used.
Another object of the present invention is to provide a self-ejecting key device for drill chucks that has relatively few parts and is particularly well adapted for ease and economy of manufacture.